The present invention relates to artificial muscles and, in particular, it concerns hydraulic actuated artificial muscles for use with orthetic devices, prosthetic devices or as an actuator for other applications in medical and robotic devices.
The principles of hydraulics have been used in the development of innumerable devices where pushing or pulling forces were need. These were generally based on rigid hydraulic cylinders and pistons. Recent years have seen the development of pushing and pulling devices that are intended to imitate muscle tissue both in the manner in which they operate and in texture. As a result, there is now a class of devices generally referred to as xe2x80x9cmuscles.xe2x80x9d
Some of the muscle devices are based on polymers that can be made to contract as a result of chemical changes or an electric current, such as the xe2x80x9cIrrigated Musclexe2x80x9d being researched at M.I.T. (www.ai.mit.edu/projects/muscle/papers/memo1330/memo1330.html). Research is also under way at the University of New Mexico on a combination of polymer and metal strips which are made to contract by the use of electric current (www.unm. edu/%7Eamri/). Devices based on these types of technology may act in a way similar to natural muscle and may be suited to robotic applications. They may, however, be inappropriate for applications entailing close contact with a human body, such as orthetics.
Another group of artificial muscles are based on the principles of pneumatics, such as the xe2x80x9cMcKibben Musclexe2x80x9d technology of the University of Washington (http://brl.ee.washington.edu/BRL/devices/mckibben/index.html). Closely related to the pneumatic muscles are those muscle devices based on hydraulics. The obvious similarity is that movement is due to the expansion of a device component due to fluid pressure, either air pressure or liquid pressure. In fact, many of the artificial muscles in these groups may be suitable for pneumatic or hydraulic applications. These devices, also, suffer either collectively or individually from a number of drawbacks. The devices of U.S. Pat. No. 4,784,042 to Payuter, U.S. Pat. No. 5,245,885, to Robertson, 6,067,892 to Erickson and U.S. Pat. No. 6,168,643 B1 to Schmitz are representative of devices that suffer from the need to be connected to external support devices such as air compressors, hydraulic pumps and fluid reservoirs. These external support devices are usually heavy cumbersome pieces of equipment, ill suited for a target goal of bringing mobility to patients with limited or no use of one or more of their limbs. Further, these devices are able to apply force in only one direction.
The hydraulic device of U.S. Pat. No. 4,958,705 to Horvath eliminates the need for an external fluid reservoir. The pneumatic device of U.S. Pat. No. 5,800,561 to Rodriguez eliminates the need for a compressor by utilizing a small canister of compressed air. The amount of usage is reliant upon the size and pressure limitations of the canister. Both these devices, however, offer no inherent cushioning for any soft tissue they may contact.
There is therefore a need for a self-contained artificial muscle that is able to exert enough force to actuate an orthetic device or prosthetic device. That is, an artificial muscle that does not need to be connected to external support devices, such as air compressors and fluid reservoirs. It would be desirable if the artificial muscle can be directed to apply force in more than one direction; that is, either a pushing force or a pulling force, as needed. It would be further desirable if the artificial muscles could provide an amount of cushion or other protection for any soft tissue it may contact during use without the use of additional coverings.
The present invention is a hydraulic actuated artificial muscle.
According to the teachings of the present invention there is provided, a method for causing relative movement between at least two connecting elements, the at least two connecting elements being for attaching a hydraulic actuator to an application device, the method comprising: transferring fluid between at least one first expandable fluid-containing cell and at least one second expandable fluid-containing cell such that the transferring of fluid out of one of the first expandable fluid-containing cell and the second expandable fluid-containing cell and into an other of the first expandable fluid-containing cell and the second expandable fluid-containing cell thereby causing substantially simultaneous contracting of the one and expanding of the other of the first expandable fluid-containing cell and the second expandable fluid-containing cell, the transferring being performed using a pump system in fluid communication with the first expandable fluid-containing cell and the second expandable fluid-containing cell thereby forming a closed fluid system; wherein the at least one first expandable fluid-containing cell is at least partially defined by a first displaceable containment-wall, the first expandable fluid-containing cell being mechanically linked to at least a first of the connecting elements, the at least one second expandable fluid-containing cell is at least partially defined by a second displaceable containment-wall, the second expandable fluid-containing cell being mechanically linked to at least a second of the connecting elements, and at least one of the first displaceable containment-wall and second displaceable containment-wall is a flexible wall and the expanding of each the expandable fluid-containing cell generates relative movement between at least two of the connecting elements.
According to a further teaching of the present invention, the transferring is of an incompressible fluid.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that one of the first displaceable containment-wall and second displaceable containment-wall defines at least portions of both the first expandable fluid-containing cell and the second expandable fluid-containing cell.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that the first expandable fluid-containing cell substantially circumscribes the second expandable fluid-containing cell.
According to a further teaching of the present invention, the transferring is performed such that the expanding of the first expandable fluid-containing cell and the expanding of the second expandable fluid-containing cell are such that as fluid is pumped out of the first expandable fluid-containing cell and into the second expandable fluid-containing cell, the second expandable fluid-containing cell expands, thus causing the hydraulic actuator to expand longitudinally while contracting latitudinally thereby causing at least two of the connection elements to move substantially away from each other, conversely as fluid is pumped out of the second expandable fluid-containing cell and into the at least a first expandable fluid-containing cell, the first expandable fluid-containing cell expands, thus causing the hydraulic actuator to contract longitudinally while expanding latitudinally thereby causing at least two of the connection elements to move substantially toward each other.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that both the first displaceable containment-wall and the second displaceable containment-wall are implemented as flexible walls.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that the second displaceable containment-wall is implemented as a cylindrical wall of a piston element of a cylinder and piston assembly, the piston being displaceable within the cylinder.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that the first expandable fluid-containing cell is deployed on a first side of a central base, the central base including at least a first of the connecting element, and second expandable fluid-containing cell is deployed on a second side of the central base, at least a second of the connecting elements is attached to the first expandable fluid-containing cell, at least a third of the connecting elements is attached to the at least one second expandable fluid-containing cell, the expanding of the first expandable fluid-containing cell and the expanding of the second expandable fluid-containing cell are such that as the fluid is pumped out of the first expandable fluid-containing cell and into the second expandable fluid-containing cell, the second expandable fluid-containing cell expands, thereby causing a first at least two of the connection elements to move substantially away from each other, conversely as fluid is pumped out of the second expandable fluid-containing cell and into the first expandable fluid-containing cell, the first expandable fluid-containing cell expands, thereby causing a second at least two of the connection elements to move substantially away from each other.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that both the at least a first displaceable containment-wall and the at least a second displaceable containment-wall are implemented as the flexible walls.
According to a further teaching of the present invention, the transferring is performed between the at least one first expandable fluid-containing cell and the at least one second expandable fluid-containing cell configured such that the first side and the second side are substantially opposite sides of the central base.
According to a further teaching of the present invention there is also provided, the transferring being performed so as to articulate an orthetic device.
According to a further teaching of the present invention, the transferring being performed so as to articulate a prosthetic device.
There is also provided according to the teachings of the present invention, a hydraulic actuator comprising: at least two connecting elements for attaching the hydraulic actuator to an application device; at least one first expandable fluid-containing cell at least partially defined by a first displaceable containment-wall, the first expandable fluid-containing cell being mechanically linked to at least a first of the connecting elements; at least one second expandable fluid-containing cell at least partially defined by a second displaceable containment-wall, the second expandable fluid-containing cell being mechanically linked to at least a second of the connecting elements; and a pump system in fluid communication with the first expandable fluid-containing cell and the second expandable fluid-containing cell thereby forming a closed fluid system, the pump system configured to transfer fluid out of one of the first expandable fluid-containing cell and the second expandable fluid-containing cell and into an other of the first expandable fluid-containing cell and the second expandable fluid-containing cell, thereby causing substantially simultaneous contraction of the one and expansion of the other of the first expandable fluid-containing cell and the second expandable fluid-containing cell; wherein at least one of the first displaceable containment-wall and second displaceable containment-wall is a flexible wall and the expansion of each the expandable fluid-containing cell generates relative movement between at least two of the connecting elements.
According to a further teaching of the present invention, the fluid is an incompressible fluid.
According to a further teaching of the present invention, one of the first displaceable containment-wall and second displaceable containment-wall defines at least portions of both the first expandable fluid-containing cell and the second expandable fluid-containing cell.
According to a further teaching of the present invention, the first expandable fluid-containing cell substantially circumscribes the second expandable fluid-containing cell.
According to a further teaching of the present invention, the expansion of the first expandable fluid-containing cell and the expansion of the second expandable fluid-containing cell are configured such that as fluid is pumped out of the first expandable fluid-containing cell and into the second expandable fluid-containing cell, the second expandable fluid-containing cell expands, thus causing the hydraulic actuator to expand longitudinally while contracting latitudinally thereby causing at least two of the connection elements to move substantially away from each other, conversely as fluid is pumped out of the second expandable fluid-containing cell and into the at least a first expandable fluid-containing cell, the first expandable fluid-containing cell expands, thus causing the hydraulic actuator to contract longitudinally while expanding latitudinally thereby causing at least two of the connection elements to move substantially toward each other.
According to a further teaching of the present invention, both the first displaceable containment-wall and the second displaceable containment-wall are implemented as flexible walls.
According to a further teaching of the present invention, the second displaceable containment-wall is implemented as a cylindrical wall of a piston element of a cylinder and piston assembly, the piston being displaceable within the cylinder.
According to a further teaching of the present invention, the at least two connecting elements are implemented as at least three connecting elements, at least a portion of a first the connecting element being configured as a central base, at least a second the connecting element being attached to the first expandable fluid-containing cell deployed on a first side of the central base and at least a third the connecting elements being attached to the second expandable fluid-containing cell deployed on a second side of the central base, the expansion of the first expandable fluid-containing cell and the expansion of the second expandable fluid-containing cell are such that as fluid is pumped out of the first expandable fluid-containing cell and into the second expandable fluid-containing cell, the second expandable fluid-containing cell expands, thereby causing a first at least two of the connection elements to move substantially away from each other, conversely as fluid is pumped out of the second expandable fluid-containing cell and into the first expandable fluid-containing cell, the first expandable fluid-containing cell expands, thereby causing a second at least two of the connection elements to move substantially away from each other.
According to a further teaching of the present invention, both the at least a first displaceable containment-wall and the at least a second displaceable containment-wall are implemented as the flexible walls.
The hydraulic actuator of claim 20, wherein the first side and the second side are substantially opposite sides of the central base.
According to a further teaching of the present invention, the application device is an orthetic device.
According to a further teaching of the present invention, the application device is a prosthetic device.